1. Field of the Invention
This invention relates in general to methods and systems for coupling a communications unit to another electronic device and more particularly, coupling the communications unit to a hearing enhancement device.
2. Description of the Related Art
In recent years, communication units, such as cellular telephones and personal digital assistants, have become commonplace. Many users of such units may wear hearing enhancement devices, commonly referred to as hearing aids. Many hearing aids contain two types of coupling paths: (1) acoustic coupling and (2) inductive coupling. For acoustic coupling, a microphone that is within the hearing aid receives audio from an external source and transfers it to an amplification stage of the hearing aid. Regarding inductive coupling, the hearing aid typically includes an axial or radial telecoil, or T-coil. A magnetic field that is generated by an external, sound-producing device can cause a signal to be induced in the T-coil of the hearing aid, and this signal is transferred to the amplification stage. The hearing aid normally includes a switch that permits a user to select one of these coupling paths.
The Federal Communications Commission (FCC) has mandated that cellular telephone manufacturers soon produce cellular telephones that are compatible with hearing aids. The compatibility is based on standards set forth by the American National Standards Institute (ANSI). In addition, the compatibility applies to both acoustic coupling and inductive coupling.
The acoustic path for most cellular telephones, however, includes a housing, and the acoustic characteristics of the housing affect the audio frequency response of a cellular telephone. To limit the effect of the housing on the audio frequency response, many cellular telephones include an audio equalizer, which can be used to manipulate the audio signal being fed to a speaker of the cellular telephone. The audio equalizer can produce an optimal acoustic frequency response, one that is satisfactory for users who do or do not wear hearing aids. Additionally, this frequency response meets industry standards for an acoustically-coupled hearing aid.
Unfortunately, this manipulation of the audio signal produces a less-than-optimal frequency response for an inductively-coupled hearing aid. In fact, this less-than-optimal frequency response fails to meet the FCC's compatibility requirements for magnetically coupled hearing aids. Additionally, if the audio signal is adjusted to produce an optimal frequency response for an inductively-coupled hearing aid, the frequency response for an acoustically-coupled hearing aid will suffer and will fail to meet the FCC's compatibility requirement.